What's the best material and supplier for Rudder bearings

savageseadog

savageseadog

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What\'s the best material and supplier for Rudder bearings

Going to buy or make some rudder bearings. The rudder stock goes through an enclosed tube in the hull I need a bearing top and bottom. What material Delrin, Nylon PTFE Tufnol or what. Is there a guy somewhre who knocks these out on a regular basis?
The boat is a 30 footer
 
Re: What\'s the best material and supplier for Rudder bearings

Definitely not nylon. It absorbs water and can swell causing rudder siezure. Teflon should be good.
 
Re: What\'s the best material and supplier for Rudder bearings

Here in Oz people tend to use a plastic called "Ralloy" (sp?) - supposedly used for bearings on US naval subs. Definitely not nylon, as it swells in water. Have seen epoxy resin / graphite powder / cabosil mix used to form a bearing in place.
 
Re: What\'s the best material and supplier for Rudder bearings

Thordon is one of the best materials available for water lubed bearings - stay away from all regular plastics if you want a long lived installation.

Link is http://www.thordonbearings.com/ and while it talks about big ships, etc, it is readily available in small quantiites for machining up custom bearings for small boats. Distributor for UK is given in the link but any marine engineering place should be able to source it.

John
 
Re: What\'s the best material and supplier for Rudder bearings

"Bear" brand Tufnol. It is used for marine bearings and is specifically designed for such. - IMHO it is much superior to Delrin and the like and is nicer to work with.
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"Artificial intelligence is no match for natural stupidity"
 
Re: What\'s the best material and supplier for Rudder bearings

Teflon is very slippy but unfortunately also soft. You can buy it glass-loaded which will make it last longer but the generally preferred material now is UHMWPE;- ultra high molecular weight poly ethylene.

What you need most of all is a dimensioned drawing that is correct! Too often my company receives "arm-wavers" saying "you know, round and about this long with a hole in the middle".

If you get stuck, pm me.
 
Re: What\'s the best material and supplier for Rudder bearings

The problem with many plastics. such as Nylon, Delrin, Teflon, its PTFE clones, as well as UHMWPE, UMPY for slang, is that with only a little heat and pressure, they creep. While some, such as Delrin and UHMWPE are fine for cold and mild climates, they may be undesirable for a boat operating even for a short time in a hot climate where it is likely that at least part of the structure will be exposed to and as a result get hot from severe sun exposure.
Bearing materials that are suitable for rudder bearings, regardless of weather conditions, in no particular order are Tufnol, Orkot, and Maritex, amongst others. These materials, although chemically different from each other, share a common feature in that they are all re-enforced bearing materials made from rigid thermoset resin systems. They cope very well in normal conditions, and equally well when heat and pressure is applied,either separately, or simultaneously. One other very important feature is that all three bearing materials bond with epoxy resin for two reasons, the first and most important being the chemical composition of the resin which naturally bonds to epoxy, and the second, the fibrous nature of the re-enforcement, which, when wetted with epoxy, tends to act as mechanical anchors to lock the bearing in position. A great advantage if gluing bearings inside a tube.
For the very little extra cost, they are well worth considering.
 
Re: What\'s the best material and supplier for Rudder bearings

Thanks for the reply(ies) Your point about fixing bearings (or is it bushes) is interesting. The original white plastic one creeps out of it's housing or used to until I found a fix.
 
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